Enabling S-C-L-Band Systems With Standard C-Band Modulator and Coherent Receiver Using Coherent System Identification and Nonlinear Predistortion

Abstract

One promising and competitive solution to keep up with the rapid growth in data traffic while at the same time addressing increasing network cost, is the efficient reuse of legacy optical fiber infrastructure. This is highly desirable as deployed single mode fibers represent a valuable asset in the network while new installations would require high additional investments. Multiband (MB) or ultra-wideband (UWB) systems, combined with high symbol rates and higher-order modulation formats, are promising solutions to capitalize the already existing fiber plants. In this contribution, we experimentally demonstrate S-C-L-band reception with 64 GBd dual-polarization (DP) 64-ary and 32-ary quadratureamplitude modulation (QAM) while using C-band components off-the-shelf (COTS) such as DP-IQ modulators and coherent receivers. To achieve such broadband operation with components that are not optimized for an out-of-band use, mitigation of the associated penalties is decisive. To this end, we apply an end-toend electro-optical Volterra-based coherent system identification followed by nonlinear digital predistortion of the transmitter. We achieve 150-nm operation bandwidth of the transmission system by performing only a single identification and predistortion at a reference wavelength of 1500 nm.

Ultra-wideband discrete Raman amplifier optimization for single-span S-C-L-band coherent transmission systems

“…Figure 3 shows a detailed schematic diagram of the transmission setup. A narrowlinewidth tunable laser ranging from 1450 to 1650 nm was used as the channel-under-test (CUT) and fed into an LiNBO 3 modulator driven by 120-GSa/s digital-to-analog convertor (DAC) to form a 30-GBaud DP-16QAM signal [15]. The modulated signal was then amplified by a suitable amplifier (S-band TDFA or C/Lband EDFA depending on the CUT.…”

Advanced DSP-Based Monitoring for Spatially Resolved and Wavelength-Dependent Amplifier Gain Estimation and Fault Location in C+L-Band Systems

“…As shown in the illustration, the transmitter consists of a 4-ch 92 GSa/s DACs (operated at 84 GSa/s) and a standard C-band optical multiformat transmitter composed of a set of four driver amplifiers and a LiNbO3-based dual-polarization (DP) IQ-modulator. To compensate for undesired MB impairments induced by the transmitter components, Volterra-based digital pre-distortion (DPD) was employed as it has been proven to successfully suppress transmitter (non)linear distortions in S+C+L-band systems [26]. For the Volterra DPD, we used a truncated, timeinvariant 3rd-order Volterra filter with 256 taps in the first order, and 9 taps in the second and third orders.…”

Characterization of C-Band Coherent Receiver Front-Ends for Transmission Systems Beyond S-C-L-Band

“…In this regard, roadmaps for multi-band (MB) or so-called bandwidth division multiplexing (BDM) systems from O-to U-band (1260-1675 nm) covering 59 THz in bandwidth have gained momentum [3][4][5][6]. While at the same time, the experimental research for single mode fiber is mainly limited to partially filled S-C-L-band systems up to a total bandwidth of 19.8 THz [7][8][9][10], and only recently the first experiments including a coherent reception in the E-band are presented [11], [12]. The mismatch between a full O-U-band system and the current research is partially caused by the unavailability of MB or bespoken per band transponders and hence the inevitable use of wavelength limited C-band componentsoff-the-shelf.…”